When a reactor or mixing vessel uses a single impeller to agitate the fluid contents, a vortex is generally created. This vortex is inimical to proper mixing. In order to disrupt the formation of such a vortex, baffles have been included on the inside of the reactor/mixing vessel to prevent the formation of a vortex by disrupting the flow of the contents. Alternatively, scrapers could be associated with the mixing apparatus and inserted into the reactor/mixing vessel to prevent the formation of a vortex by disrupting the flow of the contents. Such scrapers can be stationary and/or rotating.
After prolonged use, however, deposits of materials can collect unevenly on the baffles. These deposits should be removed for consistent performance, leading to downtime and subsequent loss of production output and higher production costs.
Additionally, the use of baffles and/or scrapers requires higher torque from the mixing motor. Higher torque requires, in turn, larger and more expensive motors, resulting in higher capital costs as well as higher operating costs. This higher torque can also create enough force to cause the vessel to begin to rotate if not held in place, creating additional work and/or a dangerous environment. Similarly, the impellers can push up into a cowling (when present) that creates a suction force against the user, which can be particularly difficult to handle on a hand-held mixer.
As such, a need exists for a method and apparatus that allows for proper mixing of fluids without baffles, while still eliminating vortex formation in the reaction/mixing vessel and minimizing torque and power consumption.